Thermostat



2 Sheets-Sheet 1.

(No Modelj H. A. CHASE 8v H. 1'. EATON. THERMOSTAT. 110.455,813. Patented Ju1y 14,1891.

2 Sheets-Sheet 2.

(NQ Model.)

H. A. CHASE 8v H. 1?. HATGN. THERMOSTAT. 110.455,813. Patented Ju1y14,1891.

UNITED STATns PATENT OFFICE.

HENRY A. CHASE, OF BOSTON, AND HOVARD F. EATON, OF CAMBRIDGE, MASSACHUSETTS.

THERMOSTAT.

SPECIFICATION forming part of Letters Patent No. 455,813, dated July 14, 1891.

Application filed November l, 1888. Serial No. 289,732. (No model.)

To @ZZ whom t may concern;

Be it known that we, HENRY A. CHASE, of Boston, in the county of Suffolk, and HOW- ARD F. EATON, ot' Cambridge, in the county of Middlesex, State of Massachusetts, have invented an Improvement in Thermostats, ot which the following description, in connection with the accompanying drawings, is a specification, like letters and ligures on the drawings representing like parts.

This invention has for its object to im- -pi'ove the construction of therinostats employed for changing the condition ot an electric circuit upon an excessive rise in the temperature for use in connection with a tirealarm register or receiving apparatus.

The thermostat herein described is designed for use in a closed electric circuit and to open the circuit and thereafter close it again one or more times.

bln accordance with this invention a lever normally bearing on a suitable contactiseniployed, and a bimetallic coil or other suitable device sensitive to a rise in temperature is employed to move the said lever. Another lever and co-operating contact are eniployed,thelatterlever normally remaining free from the contact, and abimetallic coil or other device is employed to move the lever and close the circuit. The coils or equivalent devices are designed to move the levers under different temperatures-as, for instance, to open the circuit at, say, 120O and to close the same at 1300. Another pair of levers and co-operating contacts is also preferably eni ployed, together with coils for each lever, which are designed toagain open and close the circuit at, say, 140O and 1500, respectively. Instead of opening the circuit, we preferably employ resistance-coils, which are normally short-circuited or shiiiited out by the levers, to be thereby introduced by the expansion of the coils or equivalent devices.

Figure 1 shows an under side view ot a thermostat embodying this invention; Fig. 2, a longitudinal section of the thermostat shown in Fig. 1; Fig. 3, a perspective View showing the operative parts 'of the thermostat; Fig. el, a plan view oli' the parts ot the thermostatshown in Fig. 3; Fig. 5, an enlarged longitudinal section of the thermostat shown in Fig. l; Fig. 0, a plan View of the shell orcasc, and Fig. 7 a diagram of the circuit to be referred to.

The plate c, supporting the operating parts, is of any suitable size and shape, and the inclosing case b is perforated and supplied with binding-posts b', the parts being designed to be secured to the ceiling or other desirable place. The binding-posts form the terminals of a circuit, including any usual fire-alarm register or receiving apparatus, (not herein showin) the same forming no part of this invention.

The frame or standard c is secured to the plate a, to which the levers c c2 are pivoted, said levers extending in opposite directions, and one of which, as c', normally resting upon or against the contact c* and the other lever c2 normally lying free from the contact c". Bimetallic coils d d are provided, acting respectively upon the levers c c2; but we desire it to be understood that in lieu of the bimetallic coils any other devices sensitive to a rise in temperature may be employed.

It is designed that the coils d d shall 'respend or operate under different degrees of temperature-as, for instance, the coil d to expand and move the lever c at, say, 1200, and the coil d to expand and move the lever c2 at, say, 1300. As the levers c and c2 are moved, the circuit will be opened and thereafter closed; but we preferably employ a resistance'coil e, whichis normally excluded by the lever c', but introduced when the lever c is moved away from its contact by the coil, so that instead of positively opening the line resistance is added to weaken the current. Another pair of levers i i? is also preferably employed, pivoted to the standard or frame z, thelever t" normally bearing upon the contact l[3 and the lever f2 normally occupying a position away from the contact [4, and a resistance-coil if is employed normally sliunted out oi excluded by the lever e.

TVith the parts as described the current passes over the wire 2, lever c', contact ci", wire 5, wire 3, lever l", contact fr", and wire l-. (See Figs. i and 7.) As the lever c is moved by the coil d away from the contact c3, the current will then pass through the resistancecoil e, and when the lever c`2 is moved by its IOO coil the resistance-coil c will be excluded,the current at such time passing over t-he wire 2, lever c2, contact cwire 5, wire 3,lever t', contact i3, and wire i. Then the lever t" is moved by its coil and its contact with broken, which coil will be understood as being responsive to a temperature greater than that to which the coils d d respond, the resistance-coil i5 will be included, the current passing over the wire 2, lever c2, contact c, Wire 5, wire 3, coil t5, wire 6, and wire et, and when the lever 2 is moved by its coil the resistance-coil will be excluded.

From the foregoing it will be readily understood that the various changes in the current made as described will be transmitted through the circuit, including the register or receiver, (not shown,) to there give the alarm in usual manner.

Thus it will be seen that by the employment of two levers, as c c2, co-operating contacts, and operating devices the circuit may be changed and restored, and by the employment of four levers c c2 t" 2 and the cooperating parts the condition of the circuit may be changed and restored twice in succession. The different circuit-changers are made to operate at different temperatures for this reason.

In automatic iire-alarms it hasl usually been customary to open the circuit at certainv temperatures, and thereby sound the alarm; but it often happens that such circuits are opened accidentally by a rise in temperature not due to the breaking out of a lire and the circuit remains open till attended to by hand.

Wth this thermostat the circuit is closed again and opened by a greater rise in temperature, then closed, and so on, a suitable register recording the same and not making it necessary to-have any outside attention to put the apparatus in order for future use.

XVe do not desire to limit our invention to the precise construction shown, as it may be variously modified and still carry out the essential features of the invention.

XVe claiml. In a thermostat, two independent levers and co-operating contacts, and means, substantially as described, effected by changes in temperature of different degrees, for moving them successively, whereby the normal condition of the circuit may be changed by one lever' and thereafter restored by the other lever, combined with an inclosin g case or shell, substantially as described.

2. In a thermostat, two independent levers and co-operating contacts, one of the levers normally resting upon or against its contact, combined with two independent co-operating devices, each sensitive to a rise in temperature of a different degree, substantially as described.

3. In a thermostat, two levers and co-operating contacts therefor, and means, substantially as described, for moving them in succession, whereby the condition ofthe circuit may be changed, combined with a resistancecoil normally shunted out by one of the said levers when resting upon its contact, substantially as described.

et. ln a thermostat, the levers c e2 and contacts e3 el, and means, substantially as described, for moving the levers, combined with a resistance-coil normally excluded by one of the said levers, which when moved in cludes the coil, to be again excluded by the movement of the other lever, substantially as described.

5. ln a thermostat, four levers and co-operating contacts,ftwo only of which normally rest upon or against the contacts, and means, substantially as described, for moving the levers, combined with resistance-coils normally shunted out by tivo of the levers, and which when included by said levers are again shunted out by the other two levers, substantially as described.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

HENRY A. CHASE. HOWARD F. EATON.

Witnessesz Bannon J. Novas, E. L. Ennnv. 

